There are two basic ways to insulate a finished attic.
Insulating dormer attic space.
If the attic kneewall spaces are used for storage then you ll have to insulate along the roof slope down to the eaves and create an air barrier at the rafters.
Rigid insulation the rigid insulation method requires the utilisation of 150mm thick insulation in between the rafters along with a 50mm air gap in order to avert cold bridging.
Do dormer bungalows and houses with attics in the roof space need a different approach to insulation.
1a attic access door.
Dormer roofs are roofs that contain rooms and can present considerable challenges when it.
If only the living space will be insulated wrap the insulation around the room s walls and ceiling and then continue along the floor of the non living space.
This can be done with spray foam or rigid foam cut to fit between rafters and foamed in place with a foam gun.
2d extend insulation into joist space to reduce air flows.
In case the space on the existing rafters is not enough you can fix a batten to the rafters underside in order to enhance the depth.
In finished attic rooms with or without dormer insulate 2a between the studs of knee walls 2b between the studs and rafters of exterior walls and roof 2c and ceilings with cold spaces above.
In this case the area behind the knee wall will be uncomfortably hot or cold.
Measure the dormer s ceilings for insulation with the tape measure if needed.
If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space.